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Dabbs J, Ericson MN, Dickie DA, Harman WD. Synthesis of 1-Azatriene Complexes of Tungsten: Metal-Promoted Ring-Opening of Dihydropyridine. Organometallics 2024; 43:1051-1056. [PMID: 38756990 PMCID: PMC11094799 DOI: 10.1021/acs.organomet.4c00108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/17/2024] [Accepted: 04/17/2024] [Indexed: 05/18/2024]
Abstract
For nearly a century, chemists have explored how transition-metal complexes can affect the physical and chemical properties of linear conjugated polyenes and heteropolyenes. While much has been written about higher hapticity complexes (η4-η6), less is known about the chemistry of their η2 analogues. Herein, we describe a general method for synthesizing 5,6-η2-(1-azatriene) tungsten complexes via a 6π-azaelectrocyclic dihydropyridine ring-opening that is promoted by the π-basic nature of {WTp(NO)(PMe3)}. This study includes detailed spectroscopic and crystallographic data for the η2-dihydropyridine and η2-1-azatriene complexes, both of which were prepared as single regio- and stereoisomers.
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Affiliation(s)
- Jonathan
D. Dabbs
- Department of Chemistry, University
of Virginia, Charlottesville, Virginia 22904, United States
| | - Megan N. Ericson
- Department of Chemistry, University
of Virginia, Charlottesville, Virginia 22904, United States
| | - Diane A. Dickie
- Department of Chemistry, University
of Virginia, Charlottesville, Virginia 22904, United States
| | - W. Dean Harman
- Department of Chemistry, University
of Virginia, Charlottesville, Virginia 22904, United States
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Siddiqi Z, Bingham TW, Shimakawa T, Hesp KD, Shavnya A, Sarlah D. Oxidative Dearomatization of Pyridines. J Am Chem Soc 2024; 146:2358-2363. [PMID: 38230893 PMCID: PMC11006438 DOI: 10.1021/jacs.3c13603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Dearomatization of pyridines is a well-established synthetic approach to access piperidines. Although remarkably powerful, existing dearomatization processes have been limited to the hydrogenation or addition of carbon-based nucleophiles to activated pyridiniums. Here, we show that arenophile-mediated dearomatizations can be applied to pyridines to directly introduce heteroatom functionalities without prior substrate activation. The arenophile platform in combination with olefin oxidation chemistry provides access to dihydropyridine cis-diols and epoxides. These previously elusive compounds are now readily accessible and can be used for the downstream preparation of diversely functionalized piperidines.
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Affiliation(s)
- Zohaib Siddiqi
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States; and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States
| | - Tanner W. Bingham
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States; and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States
| | - Tsukasa Shimakawa
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States; and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States
| | - Kevin D. Hesp
- Treeline Biosciences, 500 Arsenal St, second Floor, Watertown, Massachusetts 02472, United States
| | - Andre Shavnya
- Pfizer Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - David Sarlah
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States; and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States
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Hierlmeier G, Tosatti P, Puentener K, Chirik PJ. Arene Insertion with Pincer-Supported Molybdenum-Hydrides: Determination of Site Selectivity, Relative Rates, and Arene Complex Formation. J Am Chem Soc 2023; 145:21027-21039. [PMID: 37704186 DOI: 10.1021/jacs.3c06961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The synthesis of phosphino(oxazoline)pyridine-supported molybdenum(0) cycloocta-1,5-diene complexes is described. Exposure of these complexes to dihydrogen in the presence of an arene resulted in insertion of the substrate into the molybdenum hydride bond and afforded the corresponding molybdenum cyclohexadienyl hydrides. For mono- and disubstituted arenes, the site selectivity for insertion of the most substituted bond increases with increasing size of the substituent from methyl to ethyl, iso-propyl, and tert-butyl. In contrast, 1,3,5-trisubstituted arenes underwent insertion with exclusive site selectivity. Relative rates of insertion were determined by competition experiments and established faster insertions for electron-rich arenes. Introduction of electron-withdrawing trifluoromethyl groups on the arene resulted in decreased relative rates of insertion and an increased rate for H2 reductive elimination, favoring formation of the corresponding molybdenum η6-arene complex. Studies on the reductive elimination of the cyclohexadienyl ligand with the hydride enabled the synthesis of an enantioenriched cyclohexa-1,3-diene. This study provides new insights into the ligand requirements for catalytic arene hydrogenation and a new strategy for selective arene reduction.
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Affiliation(s)
- Gabriele Hierlmeier
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paolo Tosatti
- Department of Process Chemistry & Catalysis, F. Hoffmann-La Roche Ltd, 4070 Basel, Switzerland
| | - Kurt Puentener
- Department of Process Chemistry & Catalysis, F. Hoffmann-La Roche Ltd, 4070 Basel, Switzerland
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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